BlobClient class

Reference

Package:: @azure/storage-blob

A BlobClient represents a URL to an Azure Storage blob; the blob may be a block blob, append blob, or page blob.

Extends: StorageClient

Constructors

BlobClient(string, PipelineLike)	Creates an instance of BlobClient. This method accepts an encoded URL or non-encoded URL pointing to a blob. Encoded URL string will NOT be escaped twice, only special characters in URL path will be escaped. If a blob name includes ? or %, blob name must be encoded in the URL.
BlobClient(string, StorageSharedKeyCredential \| AnonymousCredential \| TokenCredential, StoragePipelineOptions)	Creates an instance of BlobClient. This method accepts an encoded URL or non-encoded URL pointing to a blob. Encoded URL string will NOT be escaped twice, only special characters in URL path will be escaped. If a blob name includes ? or %, blob name must be encoded in the URL.
BlobClient(string, string, string, StoragePipelineOptions)	Creates an instance of BlobClient from connection string.

Properties

accountName
containerName	The name of the storage container the blob is associated with.
credential	Such as AnonymousCredential, StorageSharedKeyCredential or any credential from the `@azure/identity` package to authenticate requests to the service. You can also provide an object that implements the TokenCredential interface. If not specified, AnonymousCredential is used.
name	The name of the blob.
url	Encoded URL string value.

Methods

abortCopyFromURL(string, BlobAbortCopyFromURLOptions)	Aborts a pending asynchronous Copy Blob operation, and leaves a destination blob with zero length and full metadata. Version 2012-02-12 and newer.
beginCopyFromURL(string, BlobBeginCopyFromURLOptions)	Asynchronously copies a blob to a destination within the storage account. This method returns a long running operation poller that allows you to wait indefinitely until the copy is completed. You can also cancel a copy before it is completed by calling `cancelOperation` on the poller. Note that the onProgress callback will not be invoked if the operation completes in the first request, and attempting to cancel a completed copy will result in an error being thrown. In version 2012-02-12 and later, the source for a Copy Blob operation can be a committed blob in any Azure storage account. Beginning with version 2015-02-21, the source for a Copy Blob operation can be an Azure file in any Azure storage account. Only storage accounts created on or after June 7th, 2012 allow the Copy Blob operation to copy from another storage account.
createSnapshot(BlobCreateSnapshotOptions)	Creates a read-only snapshot of a blob.
delete(BlobDeleteOptions)	Marks the specified blob or snapshot for deletion. The blob is later deleted during garbage collection. Note that in order to delete a blob, you must delete all of its snapshots. You can delete both at the same time with the Delete Blob operation.
deleteIfExists(BlobDeleteOptions)	Marks the specified blob or snapshot for deletion if it exists. The blob is later deleted during garbage collection. Note that in order to delete a blob, you must delete all of its snapshots. You can delete both at the same time with the Delete Blob operation.
deleteImmutabilityPolicy(BlobDeleteImmutabilityPolicyOptions)	Delete the immutablility policy on the blob.
download(number, number, BlobDownloadOptions)	Reads or downloads a blob from the system, including its metadata and properties. You can also call Get Blob to read a snapshot. In Node.js, data returns in a Readable stream readableStreamBody In browsers, data returns in a promise blobBody
downloadToBuffer(Buffer, number, number, BlobDownloadToBufferOptions)	ONLY AVAILABLE IN NODE.JS RUNTIME. Downloads an Azure Blob in parallel to a buffer. Offset and count are optional, downloads the entire blob if they are not provided. Warning: Buffers can only support files up to about one gigabyte on 32-bit systems or about two gigabytes on 64-bit systems due to limitations of Node.js/V8. For blobs larger than this size, consider <xref:downloadToFile>.
downloadToBuffer(number, number, BlobDownloadToBufferOptions)	ONLY AVAILABLE IN NODE.JS RUNTIME. Downloads an Azure Blob in parallel to a buffer. Offset and count are optional, downloads the entire blob if they are not provided. Warning: Buffers can only support files up to about one gigabyte on 32-bit systems or about two gigabytes on 64-bit systems due to limitations of Node.js/V8. For blobs larger than this size, consider <xref:downloadToFile>.
downloadToFile(string, number, number, BlobDownloadOptions)	ONLY AVAILABLE IN NODE.JS RUNTIME. Downloads an Azure Blob to a local file. Fails if the the given file path already exits. Offset and count are optional, pass 0 and undefined respectively to download the entire blob.
exists(BlobExistsOptions)	Returns true if the Azure blob resource represented by this client exists; false otherwise. NOTE: use this function with care since an existing blob might be deleted by other clients or applications. Vice versa new blobs might be added by other clients or applications after this function completes.
generateSasUrl(BlobGenerateSasUrlOptions)	Only available for BlobClient constructed with a shared key credential. Generates a Blob Service Shared Access Signature (SAS) URI based on the client properties and parameters passed in. The SAS is signed by the shared key credential of the client.
getAppendBlobClient()	Creates a AppendBlobClient object.
getBlobLeaseClient(string)	Get a <xref:BlobLeaseClient> that manages leases on the blob.
getBlockBlobClient()	Creates a BlockBlobClient object.
getPageBlobClient()	Creates a PageBlobClient object.
getProperties(BlobGetPropertiesOptions)	Returns all user-defined metadata, standard HTTP properties, and system properties for the blob. It does not return the content of the blob.
getTags(BlobGetTagsOptions)	Gets the tags associated with the underlying blob.
setAccessTier(BlockBlobTier \| PremiumPageBlobTier \| string, BlobSetTierOptions)	Sets the tier on a blob. The operation is allowed on a page blob in a premium storage account and on a block blob in a blob storage account (locally redundant storage only). A premium page blob's tier determines the allowed size, IOPS, and bandwidth of the blob. A block blob's tier determines Hot/Cool/Archive storage type. This operation does not update the blob's ETag.
setHTTPHeaders(BlobHTTPHeaders, BlobSetHTTPHeadersOptions)	Sets system properties on the blob. If no value provided, or no value provided for the specified blob HTTP headers, these blob HTTP headers without a value will be cleared.
setImmutabilityPolicy(BlobImmutabilityPolicy, BlobSetImmutabilityPolicyOptions)	Set immutablility policy on the blob.
setLegalHold(boolean, BlobSetLegalHoldOptions)	Set legal hold on the blob.
setMetadata(Metadata, BlobSetMetadataOptions)	Sets user-defined metadata for the specified blob as one or more name-value pairs. If no option provided, or no metadata defined in the parameter, the blob metadata will be removed.
setTags(Tags, BlobSetTagsOptions)	Sets tags on the underlying blob. A blob can have up to 10 tags. Tag keys must be between 1 and 128 characters. Tag values must be between 0 and 256 characters. Valid tag key and value characters include lower and upper case letters, digits (0-9), space (' '), plus ('+'), minus ('-'), period ('.'), foward slash ('/'), colon (':'), equals ('='), and underscore ('_').
syncCopyFromURL(string, BlobSyncCopyFromURLOptions)	The synchronous Copy From URL operation copies a blob or an internet resource to a new blob. It will not return a response until the copy is complete.
undelete(BlobUndeleteOptions)	Restores the contents and metadata of soft deleted blob and any associated soft deleted snapshots. Undelete Blob is supported only on version 2017-07-29 or later.
withSnapshot(string)	Creates a new BlobClient object identical to the source but with the specified snapshot timestamp. Provide "" will remove the snapshot and return a Client to the base blob.
withVersion(string)	Creates a new BlobClient object pointing to a version of this blob. Provide "" will remove the versionId and return a Client to the base blob.

Constructor Details

BlobClient(string, PipelineLike)

Creates an instance of BlobClient. This method accepts an encoded URL or non-encoded URL pointing to a blob. Encoded URL string will NOT be escaped twice, only special characters in URL path will be escaped. If a blob name includes ? or %, blob name must be encoded in the URL.

new BlobClient(url: string, pipeline: PipelineLike)

Parameters

url: string

A Client string pointing to Azure Storage blob service, such as "https://myaccount.blob.core.windows.net". You can append a SAS if using AnonymousCredential, such as "https://myaccount.blob.core.windows.net?sasString".

pipeline: PipelineLike

Call newPipeline() to create a default pipeline, or provide a customized pipeline.

BlobClient(string, StorageSharedKeyCredential | AnonymousCredential | TokenCredential, StoragePipelineOptions)

new BlobClient(url: string, credential?: StorageSharedKeyCredential | AnonymousCredential | TokenCredential, options?: StoragePipelineOptions)

Parameters

url: string

credential: StorageSharedKeyCredential | AnonymousCredential | TokenCredential

Such as AnonymousCredential, StorageSharedKeyCredential or any credential from the @azure/identity package to authenticate requests to the service. You can also provide an object that implements the TokenCredential interface. If not specified, AnonymousCredential is used.

options: StoragePipelineOptions

Optional. Options to configure the HTTP pipeline.

BlobClient(string, string, string, StoragePipelineOptions)

Creates an instance of BlobClient from connection string.

new BlobClient(connectionString: string, containerName: string, blobName: string, options?: StoragePipelineOptions)

Parameters

connectionString: string

Account connection string or a SAS connection string of an Azure storage account. [ Note - Account connection string can only be used in NODE.JS runtime. ] Account connection string example - DefaultEndpointsProtocol=https;AccountName=myaccount;AccountKey=accountKey;EndpointSuffix=core.windows.net SAS connection string example - BlobEndpoint=https://myaccount.blob.core.windows.net/;QueueEndpoint=https://myaccount.queue.core.windows.net/;FileEndpoint=https://myaccount.file.core.windows.net/;TableEndpoint=https://myaccount.table.core.windows.net/;SharedAccessSignature=sasString

containerName: string

Container name.

blobName: string

Blob name.

options: StoragePipelineOptions

Optional. Options to configure the HTTP pipeline.

Property Details

accountName

accountName: string

Property Value

string

containerName

The name of the storage container the blob is associated with.

string containerName

Property Value

string

credential

credential: StorageSharedKeyCredential | AnonymousCredential | TokenCredential

Property Value

StorageSharedKeyCredential | AnonymousCredential | TokenCredential

name

The name of the blob.

string name

Property Value

string

url

Encoded URL string value.

url: string

Property Value

string

Method Details

abortCopyFromURL(string, BlobAbortCopyFromURLOptions)

Aborts a pending asynchronous Copy Blob operation, and leaves a destination blob with zero length and full metadata. Version 2012-02-12 and newer.

function abortCopyFromURL(copyId: string, options?: BlobAbortCopyFromURLOptions)

Parameters

copyId: string

Id of the Copy From URL operation.

options: BlobAbortCopyFromURLOptions

Optional options to the Blob Abort Copy From URL operation.

Returns

Promise<BlobAbortCopyFromURLResponse>

beginCopyFromURL(string, BlobBeginCopyFromURLOptions)

Asynchronously copies a blob to a destination within the storage account. This method returns a long running operation poller that allows you to wait indefinitely until the copy is completed. You can also cancel a copy before it is completed by calling cancelOperation on the poller. Note that the onProgress callback will not be invoked if the operation completes in the first request, and attempting to cancel a completed copy will result in an error being thrown. In version 2012-02-12 and later, the source for a Copy Blob operation can be a committed blob in any Azure storage account. Beginning with version 2015-02-21, the source for a Copy Blob operation can be an Azure file in any Azure storage account. Only storage accounts created on or after June 7th, 2012 allow the Copy Blob operation to copy from another storage account.

function beginCopyFromURL(copySource: string, options?: BlobBeginCopyFromURLOptions)

Parameters

copySource: string

url to the source Azure Blob/File.

options: BlobBeginCopyFromURLOptions

Optional options to the Blob Start Copy From URL operation.

Returns

Promise<PollerLike<PollOperationState<BlobBeginCopyFromURLResponse>, BlobBeginCopyFromURLResponse>>

createSnapshot(BlobCreateSnapshotOptions)

Creates a read-only snapshot of a blob.

function createSnapshot(options?: BlobCreateSnapshotOptions)

Parameters

options: BlobCreateSnapshotOptions

Optional options to the Blob Create Snapshot operation.

Returns

Promise<BlobCreateSnapshotResponse>

delete(BlobDeleteOptions)

Marks the specified blob or snapshot for deletion. The blob is later deleted during garbage collection. Note that in order to delete a blob, you must delete all of its snapshots. You can delete both at the same time with the Delete Blob operation.

function delete(options?: BlobDeleteOptions)

Parameters

options: BlobDeleteOptions

Optional options to Blob Delete operation.

Returns

Promise<BlobDeleteResponse>

deleteIfExists(BlobDeleteOptions)

Marks the specified blob or snapshot for deletion if it exists. The blob is later deleted during garbage collection. Note that in order to delete a blob, you must delete all of its snapshots. You can delete both at the same time with the Delete Blob operation.

function deleteIfExists(options?: BlobDeleteOptions)

Parameters

options: BlobDeleteOptions

Optional options to Blob Delete operation.

Returns

Promise<BlobDeleteIfExistsResponse>

deleteImmutabilityPolicy(BlobDeleteImmutabilityPolicyOptions)

Delete the immutablility policy on the blob.

function deleteImmutabilityPolicy(options?: BlobDeleteImmutabilityPolicyOptions)

Parameters

options: BlobDeleteImmutabilityPolicyOptions

Optional options to delete immutability policy on the blob.

Returns

Promise<BlobDeleteImmutabilityPolicyResponse>

download(number, number, BlobDownloadOptions)

Reads or downloads a blob from the system, including its metadata and properties. You can also call Get Blob to read a snapshot.

In Node.js, data returns in a Readable stream readableStreamBody
In browsers, data returns in a promise blobBody

function download(offset?: number, count?: number, options?: BlobDownloadOptions)

Parameters

offset: number

From which position of the blob to download, greater than or equal to 0

count: number

How much data to be downloaded, greater than 0. Will download to the end when undefined

options: BlobDownloadOptions

Optional options to Blob Download operation.

Example usage (Node.js):

// Download and convert a blob to a string
const downloadBlockBlobResponse = await blobClient.download();
const downloaded = await streamToBuffer(downloadBlockBlobResponse.readableStreamBody);
console.log("Downloaded blob content:", downloaded.toString());

async function streamToBuffer(readableStream) {
return new Promise((resolve, reject) => {
const chunks = [];
readableStream.on("data", (data) => {
chunks.push(data instanceof Buffer ? data : Buffer.from(data));
});
readableStream.on("end", () => {
resolve(Buffer.concat(chunks));
});
readableStream.on("error", reject);
});
}

Example usage (browser):

// Download and convert a blob to a string
const downloadBlockBlobResponse = await blobClient.download();
const downloaded = await blobToString(await downloadBlockBlobResponse.blobBody);
console.log(
  "Downloaded blob content",
  downloaded
);

async function blobToString(blob: Blob): Promise<string> {
  const fileReader = new FileReader();
  return new Promise<string>((resolve, reject) => {
    fileReader.onloadend = (ev: any) => {
      resolve(ev.target!.result);
    };
    fileReader.onerror = reject;
    fileReader.readAsText(blob);
  });
}

Returns

Promise<BlobDownloadResponseParsed>

downloadToBuffer(Buffer, number, number, BlobDownloadToBufferOptions)

ONLY AVAILABLE IN NODE.JS RUNTIME. Downloads an Azure Blob in parallel to a buffer. Offset and count are optional, downloads the entire blob if they are not provided.

Warning: Buffers can only support files up to about one gigabyte on 32-bit systems or about two gigabytes on 64-bit systems due to limitations of Node.js/V8. For blobs larger than this size, consider <xref:downloadToFile>.

function downloadToBuffer(buffer: Buffer, offset?: number, count?: number, options?: BlobDownloadToBufferOptions)

Parameters

buffer: Buffer

Buffer to be fill, must have length larger than count

offset: number

From which position of the block blob to download(in bytes)

count: number

How much data(in bytes) to be downloaded. Will download to the end when passing undefined

options: BlobDownloadToBufferOptions

BlobDownloadToBufferOptions

Returns

Promise<Buffer>

downloadToBuffer(number, number, BlobDownloadToBufferOptions)

ONLY AVAILABLE IN NODE.JS RUNTIME. Downloads an Azure Blob in parallel to a buffer. Offset and count are optional, downloads the entire blob if they are not provided.

function downloadToBuffer(offset?: number, count?: number, options?: BlobDownloadToBufferOptions)

Parameters

offset: number

From which position of the block blob to download(in bytes)

count: number

How much data(in bytes) to be downloaded. Will download to the end when passing undefined

options: BlobDownloadToBufferOptions

BlobDownloadToBufferOptions

Returns

Promise<Buffer>

downloadToFile(string, number, number, BlobDownloadOptions)

ONLY AVAILABLE IN NODE.JS RUNTIME. Downloads an Azure Blob to a local file. Fails if the the given file path already exits. Offset and count are optional, pass 0 and undefined respectively to download the entire blob.

function downloadToFile(filePath: string, offset?: number, count?: number, options?: BlobDownloadOptions)

Parameters

filePath: string

offset: number

From which position of the block blob to download.

count: number

How much data to be downloaded. Will download to the end when passing undefined.

options: BlobDownloadOptions

Options to Blob download options.

Returns

Promise<BlobDownloadResponseParsed>

The response data for blob download operation, but with readableStreamBody set to undefined since its content is already read and written into a local file at the specified path.

exists(BlobExistsOptions)

Returns true if the Azure blob resource represented by this client exists; false otherwise. NOTE: use this function with care since an existing blob might be deleted by other clients or applications. Vice versa new blobs might be added by other clients or applications after this function completes.

function exists(options?: BlobExistsOptions)

Parameters

options: BlobExistsOptions

options to Exists operation.

Returns

Promise<boolean>

generateSasUrl(BlobGenerateSasUrlOptions)

Only available for BlobClient constructed with a shared key credential. Generates a Blob Service Shared Access Signature (SAS) URI based on the client properties and parameters passed in. The SAS is signed by the shared key credential of the client.

function generateSasUrl(options: BlobGenerateSasUrlOptions)

Parameters

options: BlobGenerateSasUrlOptions

Optional parameters.

Returns

Promise<string>

The SAS URI consisting of the URI to the resource represented by this client, followed by the generated SAS token.

getAppendBlobClient()

Creates a AppendBlobClient object.

function getAppendBlobClient()

Returns

AppendBlobClient

getBlobLeaseClient(string)

Get a <xref:BlobLeaseClient> that manages leases on the blob.

function getBlobLeaseClient(proposeLeaseId?: string)

Parameters

proposeLeaseId: string

Initial proposed lease Id.

Returns

BlobLeaseClient

A new BlobLeaseClient object for managing leases on the blob.

getBlockBlobClient()

Creates a BlockBlobClient object.

function getBlockBlobClient()

Returns

BlockBlobClient

getPageBlobClient()

Creates a PageBlobClient object.

function getPageBlobClient()

Returns

PageBlobClient

getProperties(BlobGetPropertiesOptions)

Returns all user-defined metadata, standard HTTP properties, and system properties for the blob. It does not return the content of the blob.

function getProperties(options?: BlobGetPropertiesOptions)

Parameters

options: BlobGetPropertiesOptions

Optional options to Get Properties operation.

Returns

Promise<BlobGetPropertiesResponse>

getTags(BlobGetTagsOptions)

Gets the tags associated with the underlying blob.

function getTags(options?: BlobGetTagsOptions)

Parameters

options: BlobGetTagsOptions

Returns

Promise<BlobGetTagsResponse>

setAccessTier(BlockBlobTier | PremiumPageBlobTier | string, BlobSetTierOptions)

Sets the tier on a blob. The operation is allowed on a page blob in a premium storage account and on a block blob in a blob storage account (locally redundant storage only). A premium page blob's tier determines the allowed size, IOPS, and bandwidth of the blob. A block blob's tier determines Hot/Cool/Archive storage type. This operation does not update the blob's ETag.

function setAccessTier(tier: BlockBlobTier | PremiumPageBlobTier | string, options?: BlobSetTierOptions)

Parameters

tier: BlockBlobTier | PremiumPageBlobTier | string

The tier to be set on the blob. Valid values are Hot, Cool, or Archive.

options: BlobSetTierOptions

Optional options to the Blob Set Tier operation.

Returns

Promise<BlobSetTierResponse>

setHTTPHeaders(BlobHTTPHeaders, BlobSetHTTPHeadersOptions)

Sets system properties on the blob. If no value provided, or no value provided for the specified blob HTTP headers, these blob HTTP headers without a value will be cleared.

function setHTTPHeaders(blobHTTPHeaders?: BlobHTTPHeaders, options?: BlobSetHTTPHeadersOptions)

Parameters

blobHTTPHeaders: BlobHTTPHeaders

If no value provided, or no value provided for the specified blob HTTP headers, these blob HTTP headers without a value will be cleared. A common header to set is blobContentType enabling the browser to provide functionality based on file type.

options: BlobSetHTTPHeadersOptions

Optional options to Blob Set HTTP Headers operation.

Returns

Promise<BlobSetHTTPHeadersResponse>

setImmutabilityPolicy(BlobImmutabilityPolicy, BlobSetImmutabilityPolicyOptions)

Set immutablility policy on the blob.

function setImmutabilityPolicy(immutabilityPolicy: BlobImmutabilityPolicy, options?: BlobSetImmutabilityPolicyOptions)

Parameters

immutabilityPolicy: BlobImmutabilityPolicy

options: BlobSetImmutabilityPolicyOptions

Optional options to set immutability policy on the blob.

Returns

Promise<BlobSetImmutabilityPolicyResponse>

setLegalHold(boolean, BlobSetLegalHoldOptions)

Set legal hold on the blob.

function setLegalHold(legalHoldEnabled: boolean, options?: BlobSetLegalHoldOptions)

Parameters

legalHoldEnabled: boolean

options: BlobSetLegalHoldOptions

Optional options to set legal hold on the blob.

Returns

Promise<BlobSetLegalHoldResponse>

setMetadata(Metadata, BlobSetMetadataOptions)

Sets user-defined metadata for the specified blob as one or more name-value pairs. If no option provided, or no metadata defined in the parameter, the blob metadata will be removed.

function setMetadata(metadata?: Metadata, options?: BlobSetMetadataOptions)

Parameters

metadata: Metadata

Replace existing metadata with this value. If no value provided the existing metadata will be removed.

options: BlobSetMetadataOptions

Optional options to Set Metadata operation.

Returns

Promise<BlobSetMetadataResponse>

setTags(Tags, BlobSetTagsOptions)

Sets tags on the underlying blob. A blob can have up to 10 tags. Tag keys must be between 1 and 128 characters. Tag values must be between 0 and 256 characters. Valid tag key and value characters include lower and upper case letters, digits (0-9), space (' '), plus ('+'), minus ('-'), period ('.'), foward slash ('/'), colon (':'), equals ('='), and underscore ('_').

function setTags(tags: Tags, options?: BlobSetTagsOptions)

Parameters

tags: Tags

options: BlobSetTagsOptions

Returns

Promise<BlobSetTagsResponse>

syncCopyFromURL(string, BlobSyncCopyFromURLOptions)

The synchronous Copy From URL operation copies a blob or an internet resource to a new blob. It will not return a response until the copy is complete.

function syncCopyFromURL(copySource: string, options?: BlobSyncCopyFromURLOptions)

Parameters

copySource: string

The source URL to copy from, Shared Access Signature(SAS) maybe needed for authentication

options: BlobSyncCopyFromURLOptions

Returns

Promise<BlobCopyFromURLResponse>

undelete(BlobUndeleteOptions)

Restores the contents and metadata of soft deleted blob and any associated soft deleted snapshots. Undelete Blob is supported only on version 2017-07-29 or later.

function undelete(options?: BlobUndeleteOptions)

Parameters

options: BlobUndeleteOptions

Optional options to Blob Undelete operation.

Returns

Promise<BlobUndeleteResponse>

withSnapshot(string)

Creates a new BlobClient object identical to the source but with the specified snapshot timestamp. Provide "" will remove the snapshot and return a Client to the base blob.

function withSnapshot(snapshot: string)

Parameters

snapshot: string

The snapshot timestamp.

Returns

BlobClient

A new BlobClient object identical to the source but with the specified snapshot timestamp

withVersion(string)

Creates a new BlobClient object pointing to a version of this blob. Provide "" will remove the versionId and return a Client to the base blob.

function withVersion(versionId: string)

Parameters

versionId: string

The versionId.

Returns

BlobClient

A new BlobClient object pointing to the version of this blob.